Watercourse and fish habitat unit address data structures and calculation procedures were developed for Grouse Creek (northern California) so address matching (geocoding) functions of a vector geographic information system (GIS--pcArcInfo) could be used to derive locations of main- and side-channel fish habitat features from previously collected habitat data sets. Habitat unit addresses were calculated using a proportioning equation to correct for the discrepancy between field-measured and digitized distances, resulting in addresses that represented the distance, in feet, of each unit from the mouth of the creek.
A 4-number address structure consisting of odd- and even-parity address values was used to exploit "offset" capabilities of the address matching command. Results of address matching were creation of a point topology coverage with each marker representing the downstream end-point of a habitat unit. The 4-number address structure facilitated intuitive, graphic representations of main- and side-channel habitat features left and right, respectively, of the watercourse arc (as if facing upstream).
The hydrologic unit code (HUC) was used as an address zone attribute, which can significantly reduce address ambiguity and the need for address rejection processing. The habitat unit address structure could be used as a compound primary key, providing unique database and spatial identity to any in-stream fish habitat unit in the continental United States. The HUC served as a "landscape resource zip code" in the address structure and also enables relational access to EPA and USGS hydrologic databases.
Michael F. Martischang
USDA Forest Service
Six Rivers National Forest
1330 Bayshore Way
Eureka, CA 95501-3834
Telephone: 707-441-3587
Fax: 707-442-9242
Email: fswa/s=m.martischang/ou=r05f10a@mhs.attmail.com
Steven A. Carlson
College of Natural Resources And Science
Dept. of Natural Resource Planning & Interpretation
Humboldt State University
Arcata, CA 95521-4957
Telephone: 707-826-3438
Fax: 707-826-4145
Email: carlsons@axe.humboldt.edu